• Issue front cover thumbnail

      Volume 41, Issue 1

      March 2016,   pages  1-167

    • Long-drawn-out story

      Durgadas P Kasbekar

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    • Peculiarities of insight: Clinical implications of self-representations

      Anjali Bhat

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    • What history tells us XL. The success story of the expression ‘genome editing’

      Michel Morange

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    • Phase variation of Opa proteins of Neisseria meningitidis and the effects of bacterial transformation

      Manish Sadarangani J Claire Hoe Katherine Makepeace Peter Van Der Ley Andrew J Pollard

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      Opa proteins are major proteins involved in meningococcal colonization of the nasopharynx and immune interactions. Opa proteins undergo phase variation (PV) due to the presence of the 5′-CTCTT-3′ coding repeat (CR) sequence. The dynamics of PV of meningococcal Opa proteins is unknown. Opa PV, including the effect of transformation on PV, was assessed using a panel of Opa-deficient strains of Neisseria meningitidis. Analysis of Opa expression from UK disease-causing isolates was undertaken. Different opagenes demonstrated variable rates of PV, between 6.4 ×104 and 6.9 ×103 per cell per generation. opa genes with a longer CR tract had a higher rate of PV (r2=0.77, p=0.1212). Bacterial transformation resulted in a 180-fold increase in PV rate. The majority of opagenes in UK disease isolates (315/463, 68.0%) were in the ‘on’ phase, suggesting the importance of Opa proteins during invasive disease. These data provide valuable information for the first time regarding meningococcal Opa PV. The presence of Opa PV in meningococcal populations and high expression of Opa among invasive strains likely indicates the importance of this protein in bacterial colonization in the human nasopharynx. These findings have potential implications for development of vaccines derived from meningococcal outer membranes.

    • Male function for ensuring pollination and reproductive success in Berberis lycium Royle: A novel mechanism

      Supriya Sharma Verma Susheel

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      In Berberis lycium anthers on alternate stamens dehisce, thus prolonging the male function so that pollination is affected and reproduction is ensured. The large pollen sac of each bithecous anther after the appearance of longitudinal dehiscence slit moves away from the filament while remaining attached at the tip of the connective and then orients in such a way that pollen-laden surface faces the stigma. No pollen is available to receptive stigma as pollen grains remain stuck to the anther sac. They do not get dispersed even by wind. Pollination and consequently reproduction is ensured through the intervention of insect, which does not affect pollen transfer to the stigma directly but by touching the base of the staminal filament while foraging nectar secreted by nectaries at the base of corolla, thus leading to staminal movement. This makes the dehisced anthers stick to the stigma and deposit pollen there.

    • A putative Type IIS restriction endonuclease GeoICI from Geobacillus sp. – A robust, thermostable alternative to mezophilic prototype BbvI

      Joanna Zebrowska Olga Zołnierkiewicz Marta A Skowron Agnieszka Zylicz-Stachula Joanna Jezewska-Frackowiak Piotr M Skowron

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      Screening of extreme environments in search for novel microorganisms may lead to the discovery of robust enzymes with either new substrate specificities or thermostable equivalents of those already found in mesophiles, better suited for biotechnology applications. Isolates from Iceland geysers’ biofilms, exposed to a broad range of temperatures, from ambient to close to water boiling point, were analysed for the presence of DNA-interacting proteins, including restriction endonucleases (REases). GeoICI, a member of atypical Type IIS REases, is the most thermostable isoschizomer of the prototype BbvI, recognizing/cleaving 5′-GCAGC(N8/12)-3′ DNA sequences. As opposed to the unstable prototype, which cleaves DNA at 30°C, GeoICI is highly active at elevated temperatures, up to 73°C and over a very wide salt concentration range. Recognition/cleavage sites were determined by: (i) digestion of plasmid and bacteriophage lambda DNA (λ); (ii) cleavage of custom PCR substrates, (iii) run-off sequencing of GeoICI cleavage products and (iv) shotgun cloning and sequencing of λ DNA fragmented with GeoICI. Geobacillus sp. genomic DNA was PCR-screened for the presence of other specialized REases-MTases and as a result, another putative REase-MTase, GeoICII, related to the Thermus sp. family of bifunctional REases-methyltransferases (MTases) was detected.

    • Environmental fluctuations do not select for increased variation or population-based resistance in Escherichia coli

      Shraddha Madhav Karve Kanishka Tiwary S Selveshwari Sutirth Dey

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      Little is known about the mechanisms that enable organisms to cope with unpredictable environments. To address this issue, we used replicate populations of Escherichia coli selected under complex, randomly changing environments. Under four novel stresses that had no known correlation with the selection environments, individual cells of the selected populations had significantly lower lag and greater yield compared to the controls. More importantly, there were no outliers in terms of growth, thus ruling out the evolution of population-based resistance. We also assayed the standing phenotypic variation of the selected populations, in terms of their growth on 94 different substrates. Contrary to expectations, there was no increase in the standing variation of the selected populations, nor was there any significant divergence from the ancestors. This suggested that the greater fitness in novel environments is brought about by selection at the level of the individuals, which restricts the suite of traits that can potentially evolve through this mechanism. Given that day-to-day climatic variability of the world is rising, these results have potential public health implications. Our results also underline the need for a very different kind of theoretical approach to study the effects of fluctuating environments.

    • Identification of EhTIF-IA: The putative E. histolytica orthologue of the human ribosomal RNA transcription initiation factor-IA

      Ankita Srivastava Alok Bhattacharya Sudha Bhattacharya Gagan Deep Jhingan

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      Initiation of rDNA transcription requires the assembly of a specific multi-protein complex at the rDNA promoter containing the RNA Pol I with auxiliary factors. One of these factors is known as Rrn3P in yeast and Transcription Initiation Factor IA (TIF-IA) in mammals. Rrn3p/TIF-IA serves as a bridge between RNA Pol I and the pre-initiation complex at the promoter. It is phosphorylated at multiple sites and is involved in regulation of rDNA transcription in a growth-dependent manner. In the early branching parasitic protist Entamoeba histolytica, the rRNA genes are present exclusively on circular extra chromosomal plasmids. The protein factors involved in regulation of rDNA transcription in E. histolytica are not known. We have identified the E. histolytica equivalent of TIF-1A (EhTIF-IA) by homology search within the database and was further cloned and expressed. Immuno-localization studies showed that EhTIF-IA co-localized partially with fibrillarin in the peripherally localized nucleolus. EhTIF-IA was shown to interact with the RNA Pol I-specific subunit RPA12 both in vivo and in vitro. Mass spectroscopy data identified RNA Pol I-specific subunits and other nucleolar proteins to be the interacting partners of EhTIF-IA. Our study demonstrates for the first time a conserved putative RNA Pol I transcription factor TIF-IA in E. histolytica.

    • Laser stimulation of the acupoint ‘Zusanli’ (ST.36) on the radiopharmaceutical biodistribution in Wistar rats

      Eric Hff Frederico Ailton A Santos Danubia C Sa-Caputo Rosane F Neves Carlos As Guimaraes Shyang Chang Mario Bernardo-Filho

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      Laser used to stimulate acupoints is called laser acupuncture (LA). It is generally believed that similar clinical responses to manual acupuncture can be achieved. Here we analysed the effects of the laser (904 nm) at the ‘Zusanli’ acupoint (ST.36) of the stomach meridian on the biodistribution of the radiopharmaceutical Na 99mTcO4. Wistar rats were divided into control (CG) and experimental groups (EG). The EG were exposed daily to the laser (904 nm) at ST.36 with 1 joule/min (40 mW/cm2) for 1 min. The animals of the CG were not exposed to laser at all. On the 8th day after LA, the animals were sedated and Na 99mTcO4 was administered. After 10 min, the animals were all sacrificed and the organs removed. The radioactivity was counted in each organ to calculate the percentage of radioactivity of the injected dose per gram (%ATI/g). Comparison of the %ATI/g in EG and CG was performed by Mann-Whitney test. The %ATI/g was significantly increased in the thyroid due to the stimulation of the ST.36 by laser. It is possible to conclude that the stimulation of ST.36 does lead to biological phenomena that interfere with the metabolism of the thyroid.

    • Zinc finger protein 521 overexpression increased transcript levels of Fndc5 in mouse embryonic stem cells

      Motahere-Sadat Hashemi Abbas Kiani Esfahani Maryam Peymani Alireza Shoaraye Nejati Kamran Ghaedi Mohammad Hossein Nasr-Esfahani Hossein Baharvand

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      Zinc finger protein 521 is highly expressed in brain, neural stem cells and early progenitors of the human hematopoietic cells. Zfp521 triggers the cascade of neurogenesis inmouse embryonic stemcells through inducing expression of the early neuroectodermal genes Sox1, Sox3 and Pax6. Fndc5, a precursor of Irisin has inducing effects on the expression level of brain derived neurotrophic factor in hippocampus. Therefore, it is most likely that Fndc5 may play an important role in neural differentiation. To exhibit whether the expression of this protein is under regulation with Zfp521, we overexpressed Zfp521 in a stable transformants of mESCs expressing EGFP under control of Fndc5 promoter. Increased expression of Zfp521 enhanced transcription levels of both EGFP and endogenous Fndc5. This result was confirmed by overexpression the aforementioned vectors in HEK cells and indicated that Zfp521 functions upstream of Fndc5 expression. It is most likely that Zfp521 may act through the binding to its response element on Fndc5 core promoter. Therefore it is concluding that an enhanced expression of Fndc5 in neural progenitor cells is stimulated by Zfp521 overexpression in these cells.

    • MiR-128b is down-regulated in gastric cancer and negatively regulates tumour cell viability by targeting PDK1/Akt/NF-κB axis

      Ling Zhang Jun Lei Zi-Ling Fang Jian-Ping Xiong

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      Gastric cancer (GC) is the fourth most prevalent type of cancer worldwide, which is usually caused by the interaction between environmental and genetic factors, or epigenetic aspects. Referring to the non-coding RNAs, miR-128b has been reported to be associated with many tumour cases, and exerts distinct functions in different types of cancers. However, the function of miR-128b in GC onset and progression largely remains unknown. In the present study, we found that miR-128b expression was down-regulated in tissues from 18 GC patients and 3 carcinoma cell lines. In turn, over-expression of miR-128b suppressed GC cell proliferation, invasion and promoted apoptosis. Moreover, miR-128b was predicted to bind the 3'UTR of PDK1 gene using bioinformatic target-screening tools. Accordingly, ectopic expression of miR-128b inhibited the PDK1 expression at both transcriptional and post-transcriptional levels, and furthermore, the expression of gene tailed by the 3′UTR of PDK1 gene was significantly decreased in a dualluciferase reporter assay, suggesting that PDK1 was a direct target of miR-128b in GC cells. In the conditon of miR-128b over-expression, we also observed spontaneous inactivation of the Akt/NF-κB signalling, implying PDK1 was a potential regulator of this pathway. In conclusion, our study shed some novel light on miR-128b-PDK1/Akt/NF-κB axis on GC progression.

    • Cystathionine-γ-lyase gene silencing with siRNA in monocytes/ macrophages attenuates inflammation in cecal ligation and puncture-induced sepsis in the mouse

      A Badiei ST Chambers RR Gaddam M Bhatia

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      Hydrogen sulphide is an endogenous inflammatory mediator produced by cystathionine-γ-lyase (CSE) in macrophages. To determine the role of H2S and macrophages in sepsis, we used small interference RNA (siRNA) to target the CSE gene and investigated its effect in a mouse model of sepsis. Cecal ligation puncture (CLP)-induced sepsis is characterized by increased levels of myeloperoxidase (MPO) activity, morphological changes in liver and pro-inflammatory cytokines and chemokines in the liver and lung. SiRNA treatment attenuated inflammation in the liver and lungs of mice following CLP-induced sepsis. Liver MPO activity increased in CLP-induced sepsis and treatment with siRNA significantly reduced this. Similarly, lung MPO activity increased following induction of sepsis with CLP while siRNA treatment significantly reduced MPO activity. Liver and lung cytokine and chemokine levels in CLP-induced sepsis reduced following treatment with siRNA. These findings show a crucial pro-inflammatory role for H2S synthesized by CSE in macrophages in sepsis and suggest CSE gene silencing with siRNA as a potential therapeutic approach for this condition.

    • Do prion protein gene polymorphisms induce apoptosis in non-mammals?

      Tugce Birkan Mesut Sahin Zubeyde Oztel Erdal Balcan

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      Genetic variations such as single nucleotide polymorphisms (SNPs) in prion protein coding gene, Prnp, greatly affect susceptibility to prion diseases in mammals. Here, the coding region of Prnp was screened for polymorphisms in redeared turtle, Trachemys scripta. Four polymorphisms, L203V, N205I, V225A and M237V, were common in 15 out of 30 turtles; in one sample, three SNPs, L203V, N205I and M237V, and in the remaining 14 samples, only L203V and N205I polymorphisms, were investigated. Besides, C658T, C664T, C670A and C823A SNPs were silent mutations. To elucidate the relationship between the SNPs and apoptosis, TUNEL assays and active caspase-3 immunodetection techniques in brain sections of the polymorphic samples were performed. The results revealed that TUNEL-positive cells and active caspase-3-positive cells in the turtles with four polymorphisms were significantly increased compared with those of the turtles with two polymorphisms (P<0.01 and P<0.05, respectively). In conclusion, this study provides preliminary information about the possible relationship between SNPs within the Prnp locus and apoptosis in a non-mammalian species, Trachemys scripta, in which prion disease has never been reported.

    • Identification and validation of a virus-inducible ta-siRNA-generating TAS4 locus in tomato

      Archana Singh Shradha Saraf Indranil Dasgupta Sunil Kumar Mukherjee

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      Trans-acting small interfering RNAs (ta-siRNAs) are a class of endogenous small RNA, associated with posttranscriptional gene silencing. Their biogenesis requires an initial microRNA (miRNA)-mediated cleavage of precursor RNA. Around 20 different ta-siRNA-producing loci (TASs), whose sequences are conserved, are reported in plants. In tomato, two TAS gene families have been identified, which are found to target auxin response factor gene and bacterial spot disease resistance protein Bs4 gene. Using high-throughput computational and experimental approach, we identified a new locus-producing ta-siRNA in tomato. We have also identified the putative miRNA regulating the production of ta-siRNA from this locus. The ta-siRNAs generated from TAS4 were up-regulated upon infection with a DNA virus. The potential targets of ta-siRNAs were predicted to be variety of proteins including MYB transcription factors and cell cycle regulators for some of the ta-siRNAs produced.

    • Transcriptome analysis of stem wood of Nothapodytes nimmoniana (Graham) Mabb. identifies genes associated with biosynthesis of camptothecin, an anti-carcinogenic molecule

      BL Manjunatha HR Singh G Ravikanth Karaba N Nataraja Ravi Shankar Sanjay Kumar R Uma Shaanker

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      Camptothecin (CPT), a monoterpene indole alkaloid, is a potent inhibitor of DNA topoisomerase I and has applications in treating ovarian, small lung and refractory ovarian cancers. Stem wood tissue of Nothapodytes nimmoniana (Graham) Mabb. (family Icacinaceae) is one of the richest sources of CPT. Since there is no genomic or transcriptome data available for the species, the present work sequenced and analysed transcriptome of stem wood tissue on an Illumina platform. From a total of 77,55,978 reads, 9,187 transcripts were assembled with an average length of 255 bp. Functional annotation and categorization of these assembled transcripts unraveled the transcriptome architecture and also a total of 13 genes associated with CPT biosynthetic pathway were identified in the stem woodtissue. Four genes of the pathway were cloned to full length by RACE to validate the transcriptome data. Expression analysis of 13 genes associated with CPT biosynthetic pathway in 11 different tissues vis-a-vis CPT content analysis suggested an important role of NnPG10H, NnPSLS and NnPSTR genes in the biosynthesis of CPT. These results indicated that CPT might be synthesized in the leaves and then perhaps exported to stem wood tissue for storage.

    • In silico dissection of Type VII Secretion System components across bacteria: New directions towards functional characterization

      Chandrani Das Tarini Shankar Ghosh Sharmila S Mande

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      Type VII Secretion System (T7SS) is one of the factors involved in virulence of Mycobacteriun tuberculosis H37Rv. Numerous research efforts have been made in the last decade towards characterizing the components of this secretion system. An extensive genome-wide analysis through compilation of isolated information is required to obtain a global view of diverse characteristics and pathogenicity-related aspects of this machinery. The present study suggests that differences in structural components (of T7SS) between Actinobacteria and Firmicutes, observed earlier in a few organisms, is indeed a global trend. A few hitherto uncharacterized T7SS-like clusters have been identified in the pathogenic bacteria Enterococcus faecalis, Saccharomonospora viridis, Streptococcus equi, Streptococcuss gordonii and Streptococcus sanguinis. Experimental verification of these clusters can shed lights on their role in bacterial pathogenesis. Similarly, verification of the identified variants of T7SS clusters consisting additional membrane components may help in unraveling new mechanism of protein translocation through T7SS. A database of various components of T7SS has been developed to facilitate easy access and interpretation of T7SS related data.

    • Finding clues to the riddle of sex determination in zebrafish

      A Nagabhushana Rakesh K Mishra

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      How sex is determined has been one of the most intriguing puzzles in biology since antiquity. Although a fundamental process in most metazoans, there seems to be myriad of ways in which sex can be determined – from genetic to environmental sex determination. This variation is limited mainly to upstream triggers with the core of sex determination pathway being conserved. Zebrafish has gained prominence as a vertebrate model system to study development and disease. However, very little is known about its primary sex determination mechanism. Here we review our current understanding of the sex determination in zebrafish. Zebrafish lack identifiable heteromorphic sex chromosomes and sex is determined by multiple genes, with some influence from the environment. Recently, chromosome 4 has been identified as sex chromosome along with few sex-linked loci on chromosomes 5 and 16. The identities of candidate sex-linked genes, however, have remained elusive. Sex in zebrafish is also influenced by the number of meiotic oocytes in the juvenile ovary, which appear to instruct retention of the ovarian fate. The mechanism and identity of this instructive signal remain unknown. We hypothesize that sex in zebrafish is a culmination of combinatorial effects of the genome, germ cells and the environment with inputs from epigenetic factors translating the biological meaning of this interaction.

    • Human regeneration: An achievable goal or a dream?

      Sukla Ghosh

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      The main objective of regenerative medicine is to replenish cells or tissues or even to restore different body parts that are lost or damaged due to disease, injury and aging. Several avenues have been explored over many decades to address the fascinating problem of regeneration at the cell, tissue and organ levels. Here we discuss some of the primary approaches adopted by researchers in the context of enhancing the regenerating ability of mammals. Natural regeneration can occur in different animal species, and the underlying mechanism is highly relevant to regenerative medicine-based intervention. Significant progress has been achieved in understanding the endogenous regeneration in urodeles and fishes with the hope that they could help to reach our goal of designing future strategies for human regeneration.

    • Topoisomerase IB of Deinococcus radiodurans resolves guanine quadruplex DNA structures in vitro

      Hari S Misra Kota Swathi

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